1. Field of the Invention
The invention relates to a system for demarcating an area, in particular for limiting the freedom of movement of free-roaming animals, according to the preamble of claim 1.
2. Description of the Related Art
European patent 1,139,725 discloses a system for demarcating an area on which cows graze. The system comprises two or more self-propelled vehicles between which an electrified wire runs. Each of the vehicles is provided with a GPS receiver. By means of the GPS receivers, the vehicles are able to determine the distance between them. The vehicles are remotely controlled by a computer in such a manner that they move the electrified wire together. In this way, it is possible in each case to make a new part of the area available for the cows. The computer can in this case be programmed in such a manner that the vehicles move according to a predetermined pattern at predetermined points in time. In this case, the computer has to be provided with information regarding the shape and dimensions of the area, including the presence of ditches, fences and any other obstacles.
It is a drawback of the abovementioned system that it does not always make an optimum amount of grass available in practice. Some of the time, too much grass may be made available, as a result of which cows only graze in the more attractive parts of the area and defecate on grass which has not yet been eaten. By contrast, at other times, too little grass may be made available. As a result thereof, in practice, a user is forced to check whether the amount of grass which is made available is correct and, if not, to make adjustments himself, if desired.